GB2507751A

GB2507751A - Storing data files in a file system which provides reference data files

Info

Publication number: GB2507751A
Application number: GB1220084.6A
Authority: GB
Inventors: Jens-Peter Akelbein; Nils Haustein
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 2012-11-07
Filing date: 2012-11-07
Publication date: 2014-05-14
Also published as: GB201318696D0; GB2507881A; US9355108B2; US9922041B2; US10409777B2; US20190391961A1; US20140129529A1; GB201220084D0; US20160203155A1; US11221992B2; US20180113876A1

Abstract

Data files are stored in a file system (10), wherein the file system (10) provides a plurality of reference data files (12), wherein each reference data file (12) represents a group of similar data files (14). The method comprises the steps of (i) creating a new data file (14); (ii) associating the new data file (14) with one reference data file (12) thus defining an associated reference data file (12) of the plurality of reference data files (12); (iii) informing the file system (10) about the association of the new data file (14) with the associated reference data file (12); (iv) compressing the new data file (11) using the associated reference data file (12); (v) storing the compressed data file (16) together with the information about The association with the associated reference data file (12).

Description

DESCRIPTION

Storing data files in a file system The present invention relates in general to data processing systems, and in particular, to a method and a system for storing data files in a file system.

BACKGROUND

Some types of applications have the characteristic of storing large numbers highly redundant (similar) unstructured data objects (files) in a file system. One example is an application processing and storing genomic seguence data of a large number of individuals of the same species. Such applications are being used more and more in the life science industry generating significant amount of data volume and storing these as a plurality of files in file systems. In the case of applications for genomic sequence data the scanning speed of genetic seguencers increases exponentially with each new generation leading to even more data hardly to be stored on storage devices for reasonable cost. Genetic sequencers use the application programming interface (API) of a file system. For network attached storage (NAS) the data are sent via a network protocol like Network File System protocol (NFS) or Server Message Broadcast protocol (SF4B) or other alternative protocols to store the data in the NAS device using a file system internally. There are other application areas also generating very similar content to be stored in multiple files, for example applications recording, processing and storing seismic exploration data.

Some storage systems optimize storage capacity by eliminating identical copies of stored data. In some cases, stored data is divided into segments. A new segment that is desired to be

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stored is first compared against those segments already stored.

If an identical segment is already stored on the system, a reference to that segment is stored instead of storing the new segment. This is referred to as identity compression.

Despite increasing capacities of storage systems and network links, there are often benefits to reducing the size of file objects that are stored and/or transmitted. Examples of environments that would benefit include mobile devices with limited storage, communication over telephone links, or storage of reference data, which is data that is written, saved permanently, and often never again accessed. Other examples include wide-area transfers of large objects, such as scientific data sets, or over saturated links. For example in self-contained storage systems, in which all data is stored in a single location, data can take the form of files in a file system, objects in a database, or other storage device.

Numerous techniques for reducing large object sizes exist including data compression, duplicate suppression, and delta encoding. Data compression is the elimination of redundancy internally within an object. Duplicate suppression is the process of eliminating redundancy caused by identical objects.

Delta encoding or compression eliminates redundancy of an object relative to another object, which may be an earlier version of the object having the same name. A delta compression method, for example, optimizes storage capacity by comparing a new segment that is desired to be stored against those segments already stored and looking for a similar though not necessarily identical segment. If a similar segment is already stored on the system, a delta between the old and new segment is computed and a reference to the old segment and the delta is stored in place of the entire new segment.

In US 2011/0196869 Al a method for cluster storage is disclosed.

A storage system uses a cluster of nodes to store in-ooming data. In-coming data is segmented. Each segment is characterized for assignment for storage on a given node. On the given node of the cluster, segments are stored in a manner that deduplioates segment storage.

Segments are deduplicated on each node of the cluster using delta compression. Delta compression allows the use of large segments for distributing efficiently to nodes so that sequential bytes are stored close to each other on disk. Delta compression efficiently stores segments that are similar to each other by storing one base and, for other similar segments, storing only a delta from the base along with a reference to the base. If a segment is not similar to a previously stored base, the new segment is stored as a new base and possibly a delta from that base.

S UF4MARY It is an objective of the invention to provide a method for storing data files in a file system, in order to enable an efficient and secure way of handling the long time storage and quick access of large data volumes under optimized usage of CPU resources by the file system.

Another objective is to provide a system for storing data files in a file system, in order to enable an efficient and secure way of handling the long time storage and quick access of large data volumes under optimized usage of CPU resources by the file system.

These objectives are achieved by the features of the independent claims. The other claims, the drawings and the specification disclose advantageous embodiments of the invention.

According to a first aspect of the invention a method is proposed for storing data files in a file system, wherein the file system provides a plurality of reference data files, wherein each reference data file represents a group of similar data files, the method comprising the steps of (i) creating a new data file, (ii) associating the new data file with one reference data file thus defining an associated reference data file of the plurality of reference data files, (iii) informing the file system about the association of the new data file with the associated reference data file, (iv) compressing the new data file using the associated reference data file, and (v) storing the compressed data file together with the information about the association with the associated reference data file.

According to this first aspect of the invention a method is provided comprising an application generating sets of similar data files and associated reference data files which are stored in a file system which is capable to perform delta compression and delta decompression of the data files using the reference files provided.

For large volumes of data files containing similar data the presented method provides the capability to store the data files in a compressed format in a file system. Thereby the application generating the data files can associate a plurality of data files with one reference file and instruct the file system to perform compression of these data files using the reference data file in the file system. The association of reference data files with data files can also be implemented within the file system whereby a reference file is being associated with directories or partitions of the file system. All data files stored in one directory or partition are compressed using the same reference data file which is associated with this directory. The file system provides transparent access to all data just like being stored without compression. A detection of uncompressible data allows still using the file system as a general purpose file system without compression.

Thereby the association of the reference data file with the data file can be explicitly whereby the application instructs the file system about this association (via file system command, for example) or implicitly whereby the reference data file is associated with a sub-tree of the file system and the application stores said data files in said sub-tree. The association of sets of data files with a reference data file can be based on rules configured in the application based on, for example, file content, file type, origin of data.

This method enables thus a very efficient and secure way of handling the long time storage and guick access of large data volumes under optimized usage of system resources.

There exist several ways for creating a reference data file which is of course relevant for optimizing the resources of a storage system. The different possibilities depend on the origin of the data files to be stored as well as on the type of data to be handled.

Advantageously the reference data file is created comprising the steps of (i) comparing a plurality of data files concerning at least one of a part of a file content, a file type, an origin of the plurality of data files, (ii) determining a part of contents of said data files being common to said data files, and (iii) storing the part of contents in a new data file representing the associated reference data file.

A further possibility for creating a reference data file is comprising the steps of (i) determining similar data files in a file system by a text analysis of the data files and/or an analysis of a file structure of the data files, (ii) determining a part of contents of said data files being common to said data files, as well as (iii) storing the part of contents in a new data file representing the associated reference data file.

Also favorably, a reference data file may be created comprising the steps of (i) determining similar data files in a file system by determining similarity in file names of the data files stored in a directory of the file system, (ii) determining a part of contents of said data files being common to said data files, and (iii) storing the part of contents in a new data file representing the associated reference data file.

Thus a very flexible method is described for creating reference data files to be used for data compression of data file with large volume, which might be adapted according to the origin and structure of the data files to be stored.

As a further step of the method described herein, advantageously a data file is associated with a reference data file comprising the steps of (i) generating or selecting an associated reference data file for a data file to be stored in the file system, (ii) storing the associated reference data file and the data file in the file system, as well as (iii) informing the file system about the association of the data file with the associated reference data file.

Thereby the association of the reference data file with the data file can be explicitly whereby the application instructs the file system about this association (via a file system command, for example) or implicitly whereby the reference data file is asscciated with a sub-tree cf the file system and the application stores said data files in said sub-tree. The association of sets of data files with a reference data file can be based on rules configured in the application based on, for example, file content, file type, origin of data.

Favorably, as described above, associating a data file with a reference data file is performed by associating the associated reference data file with a sub-tree of the file system and storing the data file in said sub-tree. Thus the association may be handled in a very secure and easy way of file administration.

Another advantageous possibility of informing the file system about the association of a data file with the associated reference data file is by a file link command, which offers a very easy and direct way of associating information in a file system.

Tn one embodiment of the invention a data file is compressed comprising the steps of (i) receiving a data file from an application, (ii) if an information about the association with an associated reference data file is available, determining said associated reference data file, otherwise associating the data file with a default reference data file, (iii) compressing the data file using the associated reference data file, (iv) providing a comparison result about a size of the compressed data file to a size of the uncompressed data file, and (v) deciding on storing the compressed or the uncompressed data file depending on the comparison result. This method represents a very easy and transparent way of compressing data files associated to certain reference data files and by the same way representing a reliable method of decompressing the compressed data files in the respective way with the same reference data file if needed.

Favorably compressing a data file is performed by a delta compression method, which represents a reliable and widely used method for data compression.

Due to a further favorable embodiment of the invention, transliteration of a compressed data file associated with a previous associated reference data file with a new associated reference data file is performed comprising the steps of (i) decompressing the compressed data file using the previous associated reference data file and creating a previous data file, (ii) compressing the previous data file using the new associated reference data file and storing the information about the new associated reference data file with the new compressed data file. Thus the file system and its compression module further include a reliable method to perform transliteration when a data file is re-associated with a new reference file.

The above method can be extended in an advantageous manner to only perform the transliteration if the delta compression with the new reference file creates a delta compressed data file with a smaller size than the original delta compressed data file, which may comprise the steps of (i) identifying data files in the file system being compressed with said previous associated reference data file, (ii) decompressing the identified data files using the previous associated reference data file and creating for each identified data file a previous data file, (iii) compressing each of the previous data files using the new associated reference data file, (iv) providing for each of the data files a comparison result about a size being compressed with the new associated reference data file to being compressed with the previous associated reference data file, and (v) deciding for each of the data files on storing being compressed with the new associated reference data file or with the previous associated reference data file.

Favorably the reference data files may be stored on a separate computer readable storage medium than the data files and/or the compressed data files. As the reference data files represent the basis for a plurality of compressed data files they may be stored on computer readable storage media being gualified as exhibiting special performance and reliability. Further it may be advantageous if using several backup media for these separate storage media and/or using separate backup media than for the data files and/or the compressed data files.

According to further advantageous aspect of the invention a data processing program for execution in a data processing system is proposed comprising an implementation of an instruction set for performing a method as described above when the data processing program is run on a computer.

Further a computer program product is favorably proposed comprising a computer usable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to perform a method comprising the steps of (i) creating a new data file, (ii) associating the new data file with one reference data file thus defining an associated reference data file of the plurality of reference data files, (iii) informing the file system about the association of the new data file with the associated reference data file, (iv) compressing the new data file using the associated reference data file, (v) storing the compressed data -10 -file together with the information about the association with the associated reference data file.

As will be appreciated by one skilled in the art, aspects of the present invention may be embodied as a system, method or computer program product. Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a!Tcircuit,!T "module" or "system." Furthermore, aspects of the present invention may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may be utilized. The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (RUM), an erasable programmable read-only memory (EPROM or Rash memory), an optical fiber, a portable compact disc read-only memory (CD-RUM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by -11 -or in connection with an instruction execution system, apparatus, or devioe. A computer readable signal medium may include a propagated data signal with computer readable program code embodied therein, for example, in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination thereof. A computer readable signal medium may be any computer readable medium that is not a computer readable storage medium and that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmitted using any appropriate medium, including but not limited to wireless, wireline, optical fiber cable, RE', etc., or any suitable combination of the foregoing.

Computer program code for carrying out operations for aspects of the present invention may be written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider) -12 -Aspects of the present invention are described below with reference to block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer readable medium that can direct a computer, other programmable data processing apparatus, or other devices to function in a particular manner, such that the instructions stored in the computer readable medium produce an article of manufacture including instructions which implement the function/act specified in the block diagram block or blocks.

The computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execite on the computer or other programmable apparatus provide processes for implementing the functions/acts specified in the block diagram block or blocks.

Due to a further aspect of the invention, a data processing system for execution of a data processing program is proposed, -13 -comprising software code portions for performing a method described above.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF IRE DRAWINGS

The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the embodiments, but not restricted to the embodiments, wherein is shown in: Fig. 1 a system including a files association module and a compression module according to an example embodiment of the invention; Fig. 2 a file association and storage process according to an example embodiment of the invention; Fig. 3 a delta compression process in a file system according to an example embodiment of the invention; Fig. 4 a file system structure depicting attributes for a reference data file based compression method according to an example embodiment of the invention; Fig. 5 a file system with compressed data files maintaining a link to an associated reference data file according to an example embodiment of the invention; Fig. 6 a transliteration process for a compressed data file from a previous reference data file to a new reference data file according to a further example embodiment of the invention; and -14 -Fig. 7 an example embodiment of a data processing system for carrying out a method according to the invention.

DETAILED DESCRIPTION

In the drawings, like elements are referred to with equal reference numerals. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention.

For illustrating the invention, Figure 1 depicts a system 100 including a file association module 36 and a compression module 32 according to an example embodiment of the invention. The system 100 includes an application 30 running on a server 112, which on the other side is coupled via a network 116 to a server 102, where a file system 10 is configured to run. The file system 10 represents a file oriented interface to the application 30 such as a Network File System protocol (NFS) or a Server Message Broadcast protocol (SMB) . The application 30 generates and processes sets of similar data files. A file association module 36 is integrated with the application 30 and is capable to analyze the content of said data files. This enables the file association module 36 to determine data files which are similar and group similar data files in groups or set of data files. This grouping can also be based on rules given by the application 30 or the file system 10. For example one rule can be that all data files of a certain type form one group.

Another rule can be that all data files generated in a specific -15 -period of time pertain to one set of files. For each set of similar data files the file association module 36 can now automatically generate a reference data file 12. Finally the file association module 36 in conjunction with the application stores a data file 14 in file system 10 via network 116 and thereby associates the data file 14 with said reference data file 12. A compression module 32 as well as a decompression module 34 are integrated in the file system 10. According to the invention a data file 14 may be compressed using the reference data file 12 to result in a compressed data file 16 which may be stored afterwards. Details are described in the following. The decompression module 34 may on the other hand serve for decompressing a compressed data file 16 using a reference data file 12 in order to restore the original data file 14.

The file system 10 is connected to a storage device 106 comprising hard disk drives or other storage devices according to prior art. File system 10 is the entity wherein files are being organized and stored on the storage device 106. There might be multiple file systems storing files on a single storage device 106 or a plurality of storage devices. A file system 10 contains an address space using names for the stored object, called name space. The file system 10, the servers 102, 112 and the storage device 106 can also be one system. Also multiple servers 102, 112 can build a cluster in scale out architecture.

The file system 10 may be part of an operation system running on a server or may run as a firmware on a controller.

One example for an implementation of the inventive method is described based on a file system crawler (a computer program that browses a file system in a methodical, automated manner or in an orderly fashion) . Referring to Figure 1, said file system crawler represents the application 30 including the file association module 36. The file system crawler analyzes data -16 -files stored in file system 10 in a directory structure. The file system 10 includes the compression module 32. said file system crawler implements the following method to identify similar files, determine a reference data file for said similar data files and associate said reference data file with said identified similar data files, denoted by the following steps: the file system crawler selects a type of files such as, for example, text files or presentation files or spread sheets; the file system crawler determines data files of said selected file type stored in file system 10; among these files the file system crawler determines data files with similar content. This analysis can be based on a text analysis of the file or an analysis of the file structure. In one embodiment the file system crawler analyzes files with a similar file name stored in the same directory first. For said identified similar data files the file system crawler determines that part of the contents which each of said similar data files contains and stores this part of the content in a new file representing a reference data file. Said reference data file is also stored in file system 10.

The file system crawler associates said similar data files with said reference data file by instructing the compression module 32 of the file system 10. Based on this instruction the compression module 32 of the file system 10 performs delta compression based on a prior art method for said similar data files using said reference data file.

Another example for an implementation of the inventive method is the use of storing genomic sequence data. The result of such scans are very large volumes of data, in the order of 20 to 40 TBytes of data, representing several scans of genomic seguences where the information about the individual is available, too.

Such additional information can be utilized for associating reference data files based on the information of an individual.

As an example, known relationships between individuals can be -17 -used for associating the same reference data file to qenomic sequences based on the assumptions that individuals with a close relationship also share similar qenomic sequences with a smaller set of differences compared to unrelated individuals. Based on the knowledge of relationships the same reference data file can be associated to a set of individuals to store their genomic sequence data by using delta compression. Due to the smaller amount of differences the delta compression based on an appropriate reference data file the required storage space is minimized. An example can be to use the qenomic sequence data of a mother as the reference file for all children and grandchildren. The determination of such relationships is based on associated data about individuals providing qenomic sequence data as in a patient data management system. Another use case is a set of genomic sequences being scanned from the same person.

Differences in the qenomic sequence, as created by viruses or mutations, are being stored as the result of the delta compression algorithm for each scan based on one reference genomic sequence. This may also allow storing mutations of the qenomic sequence data over a longer period of time with just storing the delta. The relationship between different genomic sequences is also known by associated data being stored in a database containing the information about a patient like in a patient data management system.

For storing qenomic sequence data based on delta compression the patient data management system represented as application 30 may utilize the file system 10 for storing genomic sequence data.

Once an initial sequence data needs to be stored the application determines this sequence as the reference data file as well.

For any further data being stored the file association module 36 determines whether the stored data has a relationship to the previously stored reference data file. The determination can vary based on the information being available in the application -18 - 30. If the relationship of individuals belonging to the same family can be determined all genomic sequence data of members of this family can be associated with the reference data file being stored for the first member. In the case of storing multiple genomic sequence data for the same individual association can be done for the individual. The association based on the file system namespace can be used here i.e. if all data of the same individual is stored in the same directory. In this case the reference data file is associated by the file association module 36 to the according directory. The file association module 36 just needs to translate relationship into a directory structure being provided by the inventive system.

Figure 2 explains a file association and storage process 800 according to an example embodiment of the invention. The process 800 may be implemented in an application 30 and its embedded file association module 36. After start of the process in step 802 the application 30 generates similar data files 14 (Figure 1) in step 804 and determines if there is a reference data file 12 (Figure 1) for these similar data files 14 in step 805 by examining rules which are configured. In step 806 of the process 800 it is checked if the reference data file 12 exists already and if the answer is no the reference data file 12 will be created in step 807. In step 808 the reference data file 12 is stored and the process 800 continues to step 810.

If the reference data file 12 already existed in step 806 then the process 800 flows to step 810 where the data files 14 generated in step 804 are stored in the file system 10 (Figure 1) . In step 812 the process 800 associates the data files 14 with the reference data file 12 by sending an instruction to the file system 10. For example this instruction can be based on an existing file link command including a new option (parameter) -19 -which instructs the file system 10 to associate the reference data file 12 with the data file. Process 800 ends in step 820.

The association of the reference data file 12 with the data file 14 can be performed explicitly whereby the application instructs the file system 10 about this association (via file link command) or implicitly whereby the reference data file 12 is associated with a sub-tree 28 (Figure 6) of the file system 10 and the application stores said data files 14 in said sub-tree 28.

Reference data files may be created by one of the following steps, (i) comparing a plurality of data files 14 concerning at least one of a part of a file content, a file type, an origin of the plurality of data files 14, (ii) determining similar data files in a file system 10 by a text analysis of the data files 14 and/or an analysis of a file structure of the data files 14, (iii) determining similar data files 14 in a file system 10 by determining similarity in file names of the data files 14 stored in a directory of the file system 10, (lv) determining a part of contents of said data files 14 being common to said data files 14, and finally storing the part of contents in a new data file representing the associated reference data file 12.

Figure 3 explains a delta compression process 900 in a file system 10, which may follow the file association and storage process 800 according to an example embodiment of the invention.

Once the data files 14 and reference data file 12 is stored in the file system 10 (see Figure 1), for example by the file association and storage process 800, the compression module 32 performs the compression of said data files 14 according to process 900. The process 900 is implemented in file system 10 and its embedded compression module 32. The process 900 starts in step 902 and continues to step 904 where the data files 14, -20 -the reference data file 12 and the association instruction coming from process 800 (steps 810 and 812 in Figure 2) are received in the file system 10. In step 906 the process 900 determines the association of the data files 14 and reference data file 12 received in step 904 and determines in step 908 whether the reference data file 12 exists in the file system 10.

If the reference data file 12 does not exist in the file system the process 900 determines a default reference data file 12 in step 910. The default reference data file 12 can be set by an administrator of the file system 10. The default reference data file 12 is thereby associated with a sub-tree 28 of the file system 10, as shown in Figure 5, in which the data files 14 are stored.

In step 912 the process 900 performs delta compression of said data files 14 according to prior art methods using said reference file 12 and a compression module 32 generating a delta compressed file 16 (Figure 1) . If both files contain very similar data this algorithm becomes effective and compression factors in a range between 90% to 99% becomes achievable. This information may be processed by a second prior art compression algorithm, like a jpeg algorithm for example, for compressing the delta information. Thus a further compression factor of greater than 1000 becomes realistic.

In step 914 the process 900 checks if the size of the delta compressed data file 16 against a configurable size threshold and if the threshold is exceeded the process 900 turns to step 916 where the delta compressed data file 16 is decompressed to form the original data file 14, if it was no longer available, using a decompression module 34. In step 918 the original data file 14 is stored in the file system 10 and the process 900 ends in step 930.

-21 -If the size of the delta compressed file 16 is determined to be below the threshold in step 914 the prooess 900 turns to step 920 where the original data file 14 is deleted and the delta compressed file 16 is stored in file system 10. Subsequently the prooess 900 stores the assooiation information of the referenoe data file 12 in the delta compressed file 16 in step 922. Tn an example embodiment this information is stored in an mode (i.e. file structure information) of the delta compressed file 16. In an alternate embodiment this information may be stored in the attributes of the delta compressed file 16. The process 900 ends in step 930.

In one embodiment for large data files only a first portion of said data file 14 is compressed in step 912 and then checked against the size threshold in step 914. If the size threshold is exceeded upon compressing a first portion the original data file 14 is stored uncompressed in step 918. This embodiment allows to prevent resource intensive compression of large data files which are not compressible.

From a user or application 30 perspective the file system 10 presents the data files as original data files 14 even though the original data file 14 is compressed. This can be achieved naming the delta compressed data file 16 the same as the original data file 14 and showing the same attributes (especially size) through the interface of the file system 10.

In step 908 of process 900 in Figure 3 the existence of a referenoe data file 12 associated with one or more data files 14 is checked and if there is no reference data file 12 associated with data files 14 or the reference data file 12 is not available the process 900 introduces the concept of a default reference file 12. Thereby the administrator of the file system can associate reference data files 12 with directories or -22 -partitions of the file system 10. In step 910 of process 900 this association is checked. In Figure 4 a concept of a static association of reference data files with file system directories or partitions is explained.

Figure 4 shows a file system structure depicting attributes for a reference data file based compression method according to an example embodiment of the invention. Figure 4 therefore shows a file system 10 containing entities (directories or partitions) for subdividing the namespace and files. It divides the namespace in more manageable units allowing to apply attributes being used for rules on data file placements or other types of attributes. A sub-tree 28 of file system 10, file set 18b, has an associated attribute 40 including an association with a reference data file 12 and an attribute 42 associating a compression module 32. Once these attributes 40, 42 are associated to the file set 18b all data files being written into this file set 18b are interpreted as data files to be delta compressed using the compression module 32 associated by attribute 42 and the reference data file 12 associated by attribute 40. In addition, all data files in the remaining namespace of the file system 10, such as data files iSa, 20a, 22a-d, will be stored without any compression according to the example embodiment in Figure 4. While the example just shows the association to a file set i8b the attributes can also be associated to the file system 10, or to directories or subdirectories 20a, 20b, . . Figure 5 depicts a file system 10 with compressed data files maintaining a link to an associated reference data file according to an example embodiment of the invention, as a part of the inventive method concerning static association of reference data files based on namespaces. Figure 5 therefore shows the contents of a file system 10 with an association of -23 -the attributes 40 and 42 to a sub-tree 28 of file system 10, file set l8b like in Figure 4. After the association new data files are created and written to the file system 10 within the directory 20a. The directory 20a contained already a file lOa.

Now a new data file l6b is created in the directory 20a. The data being written into this data file 16b are processed by the delta compression module 32 referenced in attribute 42 based on the reference data file 12 referenced in attribute 40. For keeping the relationship the delta compressed data file lOb maintains a link 44 to the reference data file of attribute 40.

Tn file systems this relationship is represented within an mode (i.e. file structure information) of reference data file of attribute 40 in an mode of file 16b. Files 16c and 16d are created and written later on in the same way. Assuming the data being written to files 16b, 16c, and 16d had a correlation like to genomes from two individuals the amount of stored data in these data files is significantly smaller.

Delta compressed data files 16 can also be re-associated with new reference data files 24 whereby the compression of these data files 16 will be performed using a new reference data file 24, as is shown in Figure 6. This can be done explicitly whereby the application 30 instructs the file system 10 with its compression module 32 to associate a given data file 16 with a new reference data file 24 (for example via a file link command) . Or this can be done implicitly whereby a compressed data file 16 is copied from one directory to another directory within the files system 10 and the new directory is associated with a different reference data file 24.

Figure 6 explains this so-called transliteration process for a compressed data file 16 from a previous reference data file 12 to a new reference data file 24 according to a further example embodiment of the invention. The transliteration of a delta -24 -compressed file 16 is carried out by a decompression module 34 for extracting an uncompressed previous data file 14. In a second step of data processing the compression module 32 takes the file 14 as input and the data file 24 as the new reference data file. After processing the data files a new delta compressed data file 26 is being stored. The file 14 is stored temporarily. Alternatively, the output of the decompression module 34 is taken directly as the input of the compression module 32, not being stored in a file at all.

There are the following scenarios of handling an inheritance, i.e. a relationship to the correct associated reference data file, in detail: Scenario 1: A data file 16 is copied or moved from one part of the namespace in a file system 10 into another one i.e. from one directory to another one. If different reference data files are associated to the source and target directory the data file is transliterated by the move operation as file 26. If contents of the file 16 are moved to file 26 the file 16 gets deleted. For a copy operation the file 16 is remaining unchanged.

Scenario 2: A delta compressed file 16 is copied or moved into another part of the namespace i.e. from one directory into another one. If the target directory has no associated reference data file the delta compressed file 16 needs to be decompressed and being stored in the original format. Depending on whether a copy or move operation is carried out the file 16 gets deleted or not.

Scenario 3: A new reference data file 24 is associated to a part of the namespace i.e. a directory. All delta compressed data files 16 being stored in this directory need to be transliterated to use the new reference data file 24.

-25 -Scenario 4: A reference data file 12 is being deleted. All delta compressed data files 16 being associated to this part of the namespace are decompressed into their original data file 14.

Access to delta compressed data file 16 might be accomplished by the following way. Next to saving space on the storage device 106 being used by the data files 16, a delta information of a data file 16 based on a reference data file 12 can be used for computations itself. The data can be made accessible by just decompressing the delta compressed data file 16. Depending on the capabilities of the file system API an application 30 might access the delta information as an alternate data stream or under a different file name.

Referring now to Figure 7, a schematic of an example of a data processing system 210 is shown. Data processing system 210 is only one example of a suitable data processing system and is not intended to suggest any limitation as to the scope of use or functionality of embodiments of the invention described herein.

Regardless, data processing system 210 is capable of being implemented and/or performing any of the functionality set forth herein above.

In data processing system 210 there is a computer system/server 212, which is operational with numerous other general purpose or special purpose computing system environments or configurations.

Examples of well-known computing systems, environments, and/or configurations that may be suitable for use with computer system/server 212 include, but are not limited to, personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, multiprocessor systems, microprocessor-based systems, set top boxes, programmable consumer electronics, network PCs, minicomputer systems, -26 -mainframe computer systems, and distributed cloud computing environments that include any of the above systems or devices, and the like.

Computer system/server 212 may be described in the general context of computer system executable instructions, such as program modules, being executed by a computer system.

Generally, program modules may include routines, programs, objects, components, logic, data structures, and so on that perform particular tasks or implement particular abstract data types. Computer system/server 212 may be practiced in distributed cloud computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed cloud computing environment, program modules may be located in both local and remote computer system storage media including memory storage devices.

As shown in Figure 7, computer system/server 212 in data processing system 210 is shown in the form of a general-purpose computing device. The components of computer system/server 212 may include, but are not limited to, one or more processors or processing units 216, a system memory 228, and a bus 218 that couples various system components including system memory 228 to processor 216.

Bus 218 represents one or more of any of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, and a processor or local bus using any of a variety of bus architectures. By way of example, and not limitation, such architectures include Industry Standard Architecture (ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA) bus, Video Electronics Standards -27 -Association (VESA) local bus, and Peripheral Component Computer system/server 212 typically includes a variety of computer system readable media. Such media may be any available media that is accessible by computer system/server 212, and it includes both volatile and non-volatile media, removable and non-removable media.

System memory 228 can include computer system readable media in the form of volatile memory, such as random access memory (RAM) 230 and/or cache memory 232. Computer system/server 212 may further include other removable/non-removable, volatile/non-volatile computer system storage media. By way of example only, storage system 234 can be provided for reading from and writing to a non-removable, non-volatile magnetic media (not shown and typically called a "hard drive") . Although not shown, a magnetic disk drive for reading from and writing to a removable, non-volatile magnetic disk (e.g., a "floppy disk"), and an optical disk drive for reading from or writing to a removable, non-volatile optical disk such as a CD-ROM, DVD-ROM or other optical media can be provided. In such instances, each can be connected to bus 218 by one or more data media interfaces. As will be further depicted and described below, memory 228 may include at least one program product having a set (e.g., at least one) of program modules that are configured to carry out the functions of embodiments of the invention.

Storage system 234 may also exhibit interfaces for separate storage media for the reference data files 12 than for the data files 14 and/or the compressed data files 16, as these reference data files 12 are the basis for a plurality of compressed data files 16 and may therefore be stored on separate storage media.

Also the reference data files 12 may be backed up on separate -28 -backup media than the data files 14 and/or the compressed data files 16 as well as may be backed up on separate and/cr multiple backup media of special performance and reliability.

Program/utility 240, having a set (at least one) of program modules 242, may be stored in memory 228 by way of example, and not limitation, as well as an operating system, one or more application programs, other program modules, and program data.

Each of the operating system, one or more application programs, other program modules, and program data or some combination thereof, may include an implementation of a networking environment. Program modules 242 generally carry out the functions and/or methodologies of embodiments of the invention as described herein. Computer system/server 212 may also communicate with one or more external devices 214 such as a keyboard, a pointing device, a display 224, etc.; one or more devices that enable a user to interact with computer system/server 212; and/or any devices (e.g., network card, modem, etc.) that enable computer system/server 212 to communicate with one or more other computing devices. Such communication can occur via Input/Output (I/O) interfaces 222.

Still yet, computer system/server 212 can communicate with one or more networks such as a local area network (LAN), a general wide area network (WAN), and/or a public network (e.g., the Internet) via network adapter 220. As depicted, network adapter 220 communicates with the other components of computer system/server 212 via bus 218. It should be understood that although not shown, other hardware and/or software components could be used in conjunction with computer system/server 212.

Examples, include, but are not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data archival storage systems, etc. -29 -The block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams, and combinations of blocks in the block diagrams, can be implemented by special purpose hardware-based systems that perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.